The torque rod is publicly known as an example of a vibration isolating device for supporting the engine of the vehicle on the vehicle body in the vibration isolating manner. This torque rod includes a cylindrical rod main body and vibration isolating connecting sections provided on each end of the rod main body and having bushings. The vibration isolating connecting sections are mounted on the engine and the vehicle body, respectively.
The vibration isolating connecting section has an inner member to be mounted on the engine or vehicle body, a ring-shaped member integrally formed with the rod main body, and an insulator of elastic vibration isolating material such as rubber or the like providing a connection between the ring-shaped member and the inner member. The inner member is mounted on the vehicle body side by means of a vehicle body attachment shaft such as a bolt or the like.
With respect to the vibration isolating connecting section of the pair of vibration isolating connecting sections to be mounted on the vehicle body side, the insulator is provided with an elastic arm portion which extends from the inner member to both sides relative to the main vibration inputting direction. Extending ends of the elastic arm portion are restricted by the ring-shaped member, and the spring of the elastic arm section is different in the orthogonal three-axis directions of the inner member.
Hereinafter, with respect to the orthogonal three-axis directions, a center axis direction of the inner member shall be referred to as a Z axis, a main vibration inputting direction orthogonal to the Z axis shall be referred to as an X axis, and a direction orthogonal to each of the X axis and the Z axis shall be referred to as a Y axis. In addition, with respect to the spring of the elastic arm portion of the vibration isolating connecting section to be connected to the vehicle body side, the spring in the Z direction (the direction parallel to the Z axis shall be referred to as a Z spring, the spring in the X direction (the direction parallel to the X axis) shall be referred to as an X spring, and the spring in the Y direction (the direction parallel to the Y axis) shall be referred to as a Y spring.